The present invention relates to a wheelchair, which is provided with wheels for driving and steering the wheelchair and with at least one swivel castor, which bears part of the weight of the wheelchair and has a swivel axle, the swivel castor having a swivel range which lies in a first swivel area which includes the straight-on direction of travel of the wheelchair, and the swivel castor being freely pivotable about the swivel axle in the first swivel area.
A wheelchair of this kind is generally known. The front wheels for driving and steering can be driven by means of manual force or by means of, for example, one or more electric motors. The axes of the axles of the wheels for driving and steering generally coincide. In order to prevent the wheelchair from tipping backwards about the common axis of the front wheels, the wheelchair at the rear side has substantially freely pivotable swivel castors. The wheels for driving and steering and the swivel castors are positioned such that the mass centre comes to lie between the common axis of the wheels for driving and steering and the swivel castors. The swivel castors have the ability to pivot about the swivel axle such that they are in a position which corresponds to the direction of travel, which is determined by the front wheels, of the wheelchair.
The drawback of a wheelchair of this kind is that when taking bends the wheelchair tends to break out of the bend. This oversteer effect is caused by the centripetal force acting on the mass centre of the wheelchair. The oversteer effect occurs in particular when taking a bend at high speed.